Golf ball

ABSTRACT

A golf ball  2  has a large number of dimples  10  on a surface thereof. Fifteen axes are assumed for a phantom sphere of the golf ball  2 . 30240 points on a predetermined region of the surface of the golf ball  2  during backspin about each axis are determined. A length L 1  of a perpendicular line that extends from each point to the axis is calculated. A total length L 2  is calculated by summing 21 lengths L 1  calculated based on 21 perpendicular lines arranged in a direction of the axis. A transformed data constellation is obtained by performing Fourier transformation on a data constellation of 1440 total lengths L 2  calculated along a direction of rotation about the axis. A peak value and an order of a maximum peak of the transformed data constellation are calculated. A minimum value of 15 peak values is not less than 95 mm.

This application claims priority on Patent Application No. 2016-242133filed in JAPAN on Dec. 14, 2016. The entire contents of this JapanesePatent Application are hereby incorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to golf balls. Specifically, the presentinvention relates to dimple patterns of golf balls.

Description of the Related Art

The face of a golf club has a loft angle. When a golf ball is hit withthe golf club, backspin due to the loft angle occurs in the golf ball.The golf ball flies with the backspin.

Golf balls have a large number of dimples on the surfaces thereof. Thedimples disturb the air flow around the golf ball during flight to causeturbulent flow separation. This phenomenon is referred to as“turbulization”. Due to the turbulization, separation points of the airfrom the golf ball shift backwards leading to a reduction of drag. Theturbulization promotes the displacement between the separation point onthe upper side and the separation point on the lower side of the golfball, which results from the backspin, thereby enhancing the lift forcethat acts upon the golf ball. The reduction of drag and the enhancementof lift force are referred to as a “dimple effect”. Excellent dimplesefficiently disturb the air flow. The excellent dimples produce a longflight distance.

There have been various proposals for dimples. JPH4-109968 discloses agolf ball in which the dimple pattern of each hemisphere can be dividedinto six units. JP2004-243124 (US2004/0157682) discloses a golf ball inwhich the dimple pattern near each pole can be divided into four unitsand the dimple pattern near the equator can be divided into five units.JP2011-10667 (US2010/0326175) discloses a golf ball in which a parameterdependent on the shapes of dimples falls within a predetermined range.

The greatest interest to golf players concerning golf balls is flightperformance. Golf players desire golf balls having excellent flightperformance. In light of flight performance, there is room forimprovement of dimples.

An object of the present invention is to provide a golf ball havingexcellent flight performance.

SUMMARY OF THE INVENTION

A golf ball according to the present invention has a plurality ofdimples on a surface thereof. A minimum value of 15 peak values obtainedby executing steps (a) to (h) for each of 15 axes Ax is not less than 95mm, when spherical polar coordinates of a point that is located on asurface of a phantom sphere of the golf ball and has a latitude of θ(degrees) and a longitude of ϕ (degrees) are represented by (θ, ϕ), the15 axes Ax being

(1) a first axis Ax1 passing through a point Pn1 coordinates of whichare (75, 270) and a point Ps1 coordinates of which are (−75, 90),

(2) a second axis Ax2 passing through a point Pn2 coordinates of whichare (60, 270) and a point Ps2 coordinates of which are (−60, 90)

(3) a third axis Ax3 passing through a point Pn3 coordinates of whichare (45, 270) and a point Ps3 coordinates of which are (−45, 90),

(4) a fourth axis Ax4 passing through a point Pn4 coordinates of whichare (30, 270) and a point Ps4 coordinates of which are (−30, 90),

(5) a fifth axis Ax5 passing through a point Pn5 coordinates of whichare (15, 270) and a point Ps5 coordinates of which are (−15, 90),

(6) a sixth axis Ax6 passing through a point Pn6 coordinates of whichare (75, 0) and a point Ps6 coordinates of which are (−75, 180),

(7) a seventh axis Ax1 passing through a point Pn7 coordinates of whichare (60, 0) and a point Ps7 coordinates of which are (−60, 180),

(8) an eighth axis Ax8 passing through a point Pn8 coordinates of whichare (45, 0) and a point Ps8 coordinates of which are (−45, 180),

(9) a ninth axis Ax9 passing through a point Pn9 coordinates of whichare (30, 0) and a point Ps9 coordinates of which are (−30, 180),

(10) a tenth axis Ax10 passing through a point Pn10 coordinates of whichare (15, 0) and a point Ps10 coordinates of which are (−15, 180),

(11) an eleventh axis Ax11 passing through a point Pn11 coordinates ofwhich are (75, 90) and a point Ps11 coordinates of which are (−75, 270),

(12) a twelfth axis Ax12 passing through a point Pn12 coordinates ofwhich are (60, 90) and a point Ps12 coordinates of which are (−60, 270),

(13) a thirteenth axis Ax13 passing through a point Pn13 coordinates ofwhich are (45, 90) and a point Ps13 coordinates of which are (−45, 270),

(14) a fourteenth axis Ax14 passing through a point Pn14 coordinates ofwhich are (30, 90) and a point Ps14 coordinates of which are (−30, 270),and

(15) a fifteenth axis Ax15 passing through a point Pn15 coordinates ofwhich are (15, 90) and a point Ps15 coordinates of which are (−15, 270),the steps (a) to (h) being the steps of

(a) assuming a great circle that is present on the surface of thephantom sphere and is orthogonal to the axis Ax,

(b) assuming two small circles that are present on the surface of thephantom sphere, that are orthogonal to the axis Ax, and of whichabsolute values of central angles with the great circle are each 30°,

(c) defining a region, of the surface of the golf ball, which isobtained by dividing the surface of the golf ball at these small circlesand which is sandwiched between these small circles,

(d) determining 30240 points, on the region, arranged at intervals of acentral angle of 3° in a direction of the axis Ax and at intervals of acentral angle of 0.25° in a direction of rotation about the axis Ax,

(e) calculating a length L1 of a perpendicular line that extends fromeach point to the axis Ax,

(f) calculating a total length L2 by summing 21 lengths L1 calculated onthe basis of 21 perpendicular lines arranged in the direction of theaxis Ax,

(g) obtaining a transformed data constellation by performing Fouriertransformation on a data constellation of 1440 total lengths L2calculated along the direction of rotation about the axis Ax, and

(h) calculating a peak value and an order of a maximum peak of thetransformed data constellation. A minimum value of 15 orders obtained byexecuting the steps (a) to (h) is not less than 27. A maximum value ofthe 15 orders obtained by executing the steps (a) to (h) is not greaterthan 37. An average of the 15 orders obtained by executing the steps (a)to (h) is not less than 30 and not greater than 34.

When the golf ball according to the present invention flies, the liftforce coefficient and the drag coefficient are appropriate. The golfball has excellent flight performance.

Preferably, an average of the 15 peak values obtained by executing thesteps (a) to (h) is not less than 200 mm.

Preferably, a total volume of the dimples is not less than 450 mm³ andnot greater than 750 mm³.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a golf ball according toan embodiment of the present invention;

FIG. 2 is an enlarged front view of the golf ball in FIG. 1;

FIG. 3 is a plan view of the golf ball in FIG. 2;

FIG. 4 is a partially enlarged cross-sectional view of the golf ball inFIG. 1;

FIG. 5 is a schematic diagram for explaining an evaluation method forthe golf ball in FIG. 2;

FIG. 6 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 7 is a schematic cross-sectional view for explaining the evaluationmethod for the golf ball in FIG. 2;

FIG. 8 is a schematic cross-sectional view for explaining the evaluationmethod for the golf ball in FIG. 2;

FIG. 9 is a graph showing an evaluation result of the golf ball in FIG.2;

FIG. 10 is a graph showing another evaluation result of the golf ball inFIG. 2;

FIG. 11 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 12 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 13 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 14 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 15 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 16 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 17 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 18 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 19 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 20 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 21 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 22 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 23 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 24 is a schematic diagram for explaining the evaluation method forthe golf ball in FIG. 2;

FIG. 25 is a front view of a golf ball according to Example 2 of thepresent invention;

FIG. 26 is a plan view of the golf ball in FIG. 25;

FIG. 27 is a front view of a golf ball according to Example 3 of thepresent invention;

FIG. 28 is a plan view of the golf ball in FIG. 27;

FIG. 29 is a front view of a golf ball according to Comparative Example1;

FIG. 30 is a plan view of the golf ball in FIG. 29;

FIG. 31 is a front view of a golf ball according to Comparative Example2;

FIG. 32 is a plan view of the golf ball in FIG. 31;

FIG. 33 is a front view of a golf ball according to Comparative Example3;

FIG. 34 is a plan view of the golf ball in FIG. 33;

FIG. 35 is a front view of a golf ball according to Comparative Example4; and

FIG. 36 is a plan view of the golf ball in FIG. 35.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following will describe in detail the present invention based onpreferred embodiments with appropriate reference to the drawings.

A golf ball 2 shown in FIG. 1 includes a spherical core 4, a mid layer 6positioned outside the core 4, and a cover 8 positioned outside the midlayer 6. The golf ball 2 has a large number of dimples 10 on the surfacethereof. Of the surface of the golf ball 2, a part other than thedimples 10 is a land 12. The golf ball 2 includes a paint layer and amark layer on the external side of the cover 8 although these layers arenot shown in the drawing.

The golf ball 2 preferably has a diameter of not less than 40 mm and notgreater than 45 mm. From the standpoint of conformity to the rulesestablished by the United States Golf Association (USGA), the diameteris particularly preferably not less than 42.67 mm. In light ofsuppression of air resistance, the diameter is more preferably notgreater than 44 mm and particularly preferably not greater than 42.80mm.

The golf ball 2 preferably has a weight of not less than 40 g and notgreater than 50 g. In light of attainment of great inertia, the weightis more preferably not less than 44 g and particularly preferably notless than 45.00 g. From the standpoint of conformity to the rulesestablished by the USGA, the weight is particularly preferably notgreater than 45.93 g.

The core 4 is formed by crosslinking a rubber composition. Examples ofthe base rubber of the rubber composition include polybutadienes,polyisoprenes, styrene-butadiene copolymers, ethylene-propylene-dienecopolymers, and natural rubbers. Two or more rubbers may be used incombination. In light of resilience performance, polybutadienes arepreferable, and high-cis polybutadienes are particularly preferable.

The rubber composition of the core 4 includes a co-crosslinking agent.Examples of preferable co-crosslinking agents in light of resilienceperformance include zinc acrylate, magnesium acrylate, zincmethacrylate, and magnesium methacrylate. The rubber compositionpreferably includes an organic peroxide together with a co-crosslinkingagent. Examples of preferable organic peroxides include dicumylperoxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane,2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and di-t-butyl peroxide.

The rubber composition of the core 4 may include additives such as afiller, sulfur, a vulcanization accelerator, a sulfur compound, ananti-aging agent, a coloring agent, a plasticizer, and a dispersant. Therubber composition may include a carboxylic acid or a carboxylate. Therubber composition may include synthetic resin powder or crosslinkedrubber powder.

The core 4 has a diameter of preferably not less than 30.0 mm andparticularly preferably not less than 38.0 mm. The diameter of the core4 is preferably not greater than 42.0 mm and particularly preferably notgreater than 41.5 mm. The core 4 may have two or more layers. The core 4may have a rib on the surface thereof. The core 4 may be hollow.

The mid layer 6 is formed from a resin composition. A preferable basepolymer of the resin composition is an ionomer resin. Examples ofpreferable ionomer resins include binary copolymers formed with anα-olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbonatoms. Examples of other preferable ionomer resins include ternarycopolymers formed with: an α-olefin; an α,β-unsaturated carboxylic acidhaving 3 to 8 carbon atoms; and an α,β-unsaturated carboxylate esterhaving 2 to 22 carbon atoms. For the binary copolymer and the ternarycopolymer, preferable α-olefins are ethylene and propylene, whilepreferable α,β-unsaturated carboxylic acids are acrylic acid andmethacrylic acid. In the binary copolymer and the ternary copolymer,some of the carboxyl groups are neutralized with metal ions. Examples ofmetal ions for use in neutralization include sodium ion, potassium ion,lithium ion, zinc ion, calcium ion, magnesium ion, aluminum ion, andneodymium ion.

Instead of an ionomer resin, the resin composition of the mid layer 6may include another polymer. Examples of the other polymer includepolystyrenes, polyamides, polyesters, polyolefins, and polyurethanes.The resin composition may include two or more polymers.

The resin composition of the mid layer 6 may include a coloring agentsuch as titanium dioxide, a filler such as barium sulfate, a dispersant,an antioxidant, an ultraviolet absorber, a light stabilizer, afluorescent material, a fluorescent brightener, and the like. For thepurpose of adjusting specific gravity, the resin composition may includepowder of a metal with a high specific gravity such as tungsten,molybdenum, and the like.

The mid layer 6 has a thickness of preferably not less than 0.2 mm andparticularly preferably not less than 0.3 mm. The thickness of the midlayer 6 is preferably not greater than 2.5 mm and particularlypreferably not greater than 2.2 mm. The mid layer 6 has a specificgravity of preferably not less than 0.90 and particularly preferably notless than 0.95. The specific gravity of the mid layer 6 is preferablynot greater than 1.10 and particularly preferably not greater than 1.05.The mid layer 6 may have two or more layers.

The cover 8 is formed from a resin composition. A preferable basepolymer of the resin composition is a polyurethane. The resincomposition may include a thermoplastic polyurethane or may include athermosetting polyurethane. In light of productivity, the thermoplasticpolyurethane is preferable. The thermoplastic polyurethane includes apolyurethane component as a hard segment, and a polyester component or apolyether component as a soft segment.

The polyurethane has a urethane bond within the molecule. The urethanebond can be formed by reacting a polyol with a polyisocyanate.

The polyol, which is a material for the urethane bond, has a pluralityof hydroxyl groups. Low-molecular-weight polyols andhigh-molecular-weight polyols can be used.

Examples of an isocyanate for the polyurethane component includealicyclic diisocyanates, aromatic diisocyanates, and aliphaticdiisocyanates. Alicyclic diisocyanates are particularly preferable.Since an alicyclic diisocyanate does not have any double bond in themain chain, the alicyclic diisocyanate suppresses yellowing of the cover8. Examples of alicyclic diisocyanates include 4,4′-dicyclohexylmethanediisocyanate (H₁₂MDI), 1,3-bis(isocyanatomethyl)cyclohexane (H₆XDI),isophorone diisocyanate (IPDI), and trans-1,4-cyclohexane diisocyanate(CHDI). In light of versatility and processability, H₁₂MDI ispreferable.

Instead of a polyurethane, the resin composition of the cover 8 mayinclude another polymer. Examples of the other polymer include ionomerresins, polystyrenes, polyamides, polyesters, and polyolefins. The resincomposition may include two or more polymers.

The resin composition of the cover 8 may include a coloring agent suchas titanium dioxide, a filler such as barium sulfate, a dispersant, anantioxidant, an ultraviolet absorber, a light stabilizer, a fluorescentmaterial, a fluorescent brightener, and the like.

The cover 8 has a thickness of preferably not less than 0.2 mm andparticularly preferably not less than 0.3 mm. The thickness of the cover8 is preferably not greater than 2.5 mm and particularly preferably notgreater than 2.2 mm. The cover 8 has a specific gravity of preferablynot less than 0.90 and particularly preferably not less than 0.95. Thespecific gravity of the cover 8 is preferably not greater than 1.10 andparticularly preferably not greater than 1.05. The cover 8 may have twoor more layers.

The golf ball 2 may include a reinforcing layer between the mid layer 6and the cover 8. The reinforcing layer firmly adheres to the mid layer 6and also to the cover 8. The reinforcing layer suppresses separation ofthe cover 8 from the mid layer 6. The reinforcing layer is formed from apolymer composition. Examples of the base polymer of the reinforcinglayer include two-component curing type epoxy resins and two-componentcuring type urethane resins.

As shown in FIGS. 2 and 3, the contour of each dimple 10 is circular.The golf ball 2 has dimples A each having a diameter of 4.40 mm; dimplesB each having a diameter of 4.30 mm; dimples C each having a diameter of4.15 mm; dimples D each having a diameter of 3.90 mm; and dimples E eachhaving a diameter of 3.00 mm. The number of types of the dimples 10 isfive. The golf ball 2 may have non-circular dimples instead of thecircular dimples 10 or together with the circular dimples 10.

The number of the dimples A is 60; the number of the dimples B is 158;the number of the dimples C is 72; the number of the dimples D is 36;and the number of the dimples E is 12. The total number of the dimples10 is 338. A dimple pattern is formed by these dimples 10 and the land12.

FIG. 4 shows a cross section of the golf ball 2 along a plane passingthrough the central point of the dimple 10 and the central point of thegolf ball 2. In FIG. 4, the top-to-bottom direction is the depthdirection of the dimple 10. In FIG. 4, a chain double-dashed line 14indicates a phantom sphere 14. The surface of the phantom sphere 14 isthe surface of the golf ball 2 when it is postulated that no dimple 10exists. The diameter of the phantom sphere 14 is equal to the diameterof the golf ball 2. The dimple 10 is recessed from the surface of thephantom sphere 14. The land 12 coincides with the surface of the phantomsphere 14. In the present embodiment, the cross-sectional shape of eachdimple 10 is substantially a circular arc. The curvature radius of thiscircular arc is shown by reference character CR in FIG. 4.

In FIG. 4, an arrow Dm indicates the diameter of the dimple 10. Thediameter Dm is the distance between two tangent points Ed appearing on atangent line Tg that is drawn tangent to the far opposite ends of thedimple 10. Each tangent point Ed is also the edge of the dimple 10. Theedge Ed defines the contour of the dimple 10.

The diameter Dm of each dimple 10 is preferably not less than 2.0 mm andnot greater than 6.0 mm. The dimple 10 having a diameter Dm of not lessthan 2.0 mm contributes to turbulization. In this respect, the diameterDm is more preferably not less than 2.5 mm and particularly preferablynot less than 2.8 mm. The dimple 10 having a diameter Dm of not greaterthan 6.0 mm does not impair a fundamental feature of the golf ball 2being substantially a sphere. In this respect, the diameter Dm is morepreferably not greater than 5.5 mm and particularly preferably notgreater than 5.0 mm.

In the case of a non-circular dimple, a circular dimple 10 having thesame area as that of the non-circular dimple is assumed. The diameter ofthe assumed circular dimple 10 can be regarded as the diameter of thenon-circular dimple.

In FIG. 4, a double ended arrow Dp1 indicates a first depth of thedimple 10. The first depth Dp1 is the distance between the deepest partof the dimple 10 and the surface of the phantom sphere 14. In FIG. 4, adouble ended arrow Dp2 indicates a second depth of the dimple 10. Thesecond depth Dp2 is the distance between the deepest part of the dimple10 and the tangent line Tg.

In light of suppression of rising of the golf ball 2 during flight, thefirst depth Dp1 of each dimple 10 is preferably not less than 0.10 mm,more preferably not less than 0.13 mm, and particularly preferably notless than 0.15 mm. In light of suppression of dropping of the golf ball2 during flight, the first depth Dp1 is preferably not greater than 0.65mm, more preferably not greater than 0.60 mm, and particularlypreferably not greater than 0.55 mm.

The area S of the dimple 10 is the area of a region surrounded by thecontour line of the dimple 10 when the central point of the golf ball 2is viewed at infinity. In the case of a circular dimple 10, the area Sis calculated by the following mathematical formula.

S=(Dm/2)² *n

In the golf ball 2 shown in FIGS. 2 and 3, the area of each dimple A is15.20 mm²; the area of each dimple B is 14.52 mm²; the area of eachdimple C is 13.53 mm²; the area of each dimple D is 11.95 mm²; and thearea of each dimple E is 7.07 mm².

In the present invention, the ratio of the sum of the areas S of all thedimples 10 relative to the surface area of the phantom sphere 14 isreferred to as an occupation ratio. From the standpoint of achievingsufficient turbulization, the occupation ratio is preferably not lessthan 78%, more preferably not less than 80%, and particularly preferablynot less than 82%. The occupation ratio is preferably not greater than95%. In the golf ball 2 shown in FIGS. 2 and 3, the total area of thedimples 10 is 4695.4 mm². The surface area of the phantom sphere 14 ofthe golf ball 2 is 5728 mm², so that the occupation ratio is 82.0%.

From the standpoint of achieving a sufficient occupation ratio, thetotal number N of the dimples 10 is preferably not less than 250, morepreferably not less than 280, and particularly preferably not less than300.

From the standpoint that each dimple 10 can contribute to turbulization,the total number N of the dimples 10 is preferably not greater than 450,more preferably not greater than 400, and particularly preferably notgreater than 380.

In the present invention, the “volume V of the dimple” means the volumeof a portion surrounded by the surface of the phantom sphere 14 and thesurface of the dimple 10. The total volume TV of the dimples 10 ispreferably not less than 450 mm³ and not greater than 750 mm³. With thegolf ball 2 having a total volume TV of not less than 450 mm³, rising ofthe golf ball 2 during flight is suppressed. In this respect, the totalvolume TV is more preferably not less than 480 mm³ and particularlypreferably not less than 500 mm³. With the golf ball 2 having a totalvolume TV of not greater than 750 mm³, dropping of the golf ball 2during flight is suppressed. In this respect, the total volume TV ismore preferably not greater than 730 mm³ and particularly preferably notgreater than 710 mm³.

The golf ball 2 according to the present invention has an excellentaerodynamic characteristic. In an evaluation method for the aerodynamiccharacteristic, the following steps (a) to (h) are executed:

(a) assuming a great circle that is present on the surface of thephantom sphere 14 and is orthogonal to an axis Ax;

(b) assuming two small circles that are present on the surface of thephantom sphere 14, that are orthogonal to the axis Ax, and of which theabsolute values of central angles with the great circle are each 30°;

(c) defining a region, of the surface of the golf ball 2, which isobtained by dividing the surface of the golf ball 2 at these smallcircles and which is sandwiched between these small circles;

(d) determining 30240 points, on the region, arranged at intervals of acentral angle of 3° in a direction of the axis Ax and at intervals of acentral angle of 0.25° in a direction of rotation about the axis Ax;

(e) calculating the length L1 of a perpendicular line that extends fromeach point to the axis Ax;

(f) calculating a total length L2 by summing 21 lengths L1 calculated onthe basis of 21 perpendicular lines arranged in the direction of theaxis Ax;

(g) obtaining a transformed data constellation by performing Fouriertransformation on a data constellation of 1440 total lengths L2calculated along the direction of rotation about the axis Ax; and

(h) calculating the peak value and the order of the maximum peak of thetransformed data constellation. The following will describe each step indetail.

FIG. 5 is a schematic diagram for explaining this evaluation method.FIG. 5 shows the phantom sphere 14 of the golf ball 2. In FIG. 5,reference character NP represents a north pole. The north pole NPcorresponds to the top of a cavity face formed by an upper mold half formolding the golf ball 2. Reference character SP represents a south pole.The south pole SP corresponds to the deepest part of a cavity faceformed by a lower mold half for molding the golf ball 2. Referencecharacter Eq represents an equator. The phantom sphere 14 can be dividedinto a northern hemisphere NH and a southern hemisphere SH by theequator Eq.

The latitude of the north pole NP is 90° (degrees). The latitude θ ofthe equator Eq is zero. The latitude of the south pole SP is −90°. Thecounterclockwise direction when the phantom sphere 14 is seen from thenorth pole NP is a positive direction of longitude ϕ. The minimum valueof ϕ is zero. The maximum value of ϕ is 360°. The spherical polarcoordinates of a point present on the surface of the phantom sphere 14are represented by (θ, ϕ). In FIG. 5, a point (0, 0) is located in thefront.

In FIG. 5, reference character Loa represents a first longitude line.The longitude ϕ of the first longitude line Loa is 0° and also 360°. Thephantom sphere 14 has numerous longitude lines. A longitude line thatcontains the maximum number of dimples 10 that centrally intersect thelongitude line is defined as the first longitude line Loa. At a dimple10 that centrally intersects a longitude line, the longitude line passesthrough the area center of gravity of the dimple 10.

In this evaluation method, a first axis Ax1 is assumed. The first axisAx1 passes through a point Pn1 and a point Ps1. The point Pn1 and thepoint Ps1 are present on the surface of the phantom sphere 14. The pointPn1 is present on the northern hemisphere NH. The coordinates of thepoint Pn1 are (75, 270). The point Ps1 is present on the southernhemisphere SH. The coordinates of the point Ps1 are (−75, 90). The firstaxis Ax1 is tilted relative to the earth axis. The angle of the tilt is15°. The earth axis is a line passing through the north pole NP and thesouth pole SP.

In this evaluation method, a first great circle GC1 that is present onthe surface of the phantom sphere 14 of the golf ball 2 is assumed. Thefirst axis Ax1 is orthogonal to the first great circle GC1. In otherwords, the first axis Ax1 is orthogonal to the plane including the firstgreat circle GC1. In FIG. 5, the first great circle GC1 is tiltedrelative to the equator Eq. The angle of the tilt is 15°. The greatcircle is a circle that is present on the surface of the phantom sphere14 and has a diameter equal to the diameter of the phantom sphere 14.

The golf ball 2 rotates about the first axis Ax1. During this rotation,the circumferential speed of the first great circle GC1 is high.Therefore, the surface roughness of the golf ball 2 at and near thefirst great circle GC1 greatly influences the flight performance of thegolf ball 2.

In this evaluation method, two small circles C1 and C2 that are presenton the surface of the phantom sphere 14 and are orthogonal to the firstaxis Ax1 are assumed. FIG. 6 shows these small circles C1 and C2. Eachsmall circle is parallel to the first great circle GC1.

FIG. 7 schematically shows a partial cross section of the golf ball 2 inFIG. 6. FIG. 7 shows a cross-section passing through the center O of thegolf ball 2. The right-left direction in FIG. 7 is the direction of thefirst axis Ax1. As shown in FIG. 7, the absolute value of the centralangle between the small circle C1 and the first great circle GC1 is 30°.Although not shown, the absolute value of the central angle between thesmall circle C2 and the first great circle GC1 is also 30°. The golfball 2 is divided at the small circles C1 and C2, and of the surface ofthe golf ball 2, a region sandwiched between the small circles C1 and C2is defined. Since the circumferential speed of the first great circleGC1 is high, the dimples 10 present in this region greatly influence theaerodynamic characteristic of the golf ball 2.

In FIG. 7, a point P(α) is the point that is located on the surface ofthe golf ball 2 and of which the central angle with the first greatcircle GC1 is α° (degrees). A point F(α) is the foot of a perpendicularline Pe(α) that extends downward from the point P(α) to the first axisAx1. An arrow L1(α) represents the length of the perpendicular linePe(α). In other words, the length L1(α) is the distance between thepoint P(α) and the first axis Ax1. For one cross section, the lengthsL1(α) are calculated at 21 points P(α). Specifically, the lengths L1(α)are calculated at angles α of −30°, −27°, −24°, −21°, −18°, −15°, −12°,−9°, −6°, −3°, 0°, 3°, 6°, 9°, 12°, 15°, 18°, 21°, 24°, 27°, and 30°.The 21 lengths L1(α) are summed, thereby obtaining a total length L2(mm). The total length L2 is a parameter dependent on the surface shapein the cross section shown in FIG. 7.

FIG. 8 shows a partial cross section of the golf ball 2. In FIG. 8, adirection perpendicular to the surface of the sheet is the direction ofthe first axis Ax1. In FIG. 8, reference character β represents arotation angle of the golf ball 2. In a range of equal to or greaterthan 0° and less than 360°, the rotation angles β are set at an intervalof an angle of 0.25°. At each rotation angle, the total length L2 iscalculated. As a result, 1440 total lengths L2 are obtained along therotation direction. These total lengths L2 are a data constellationcalculated through one rotation of the golf ball 2. This dataconstellation is calculated on the basis of 30240 lengths L1.

FIG. 9 shows a graph plotting the data constellation, for the first axisAx1, of the golf ball 2 shown in FIGS. 2 and 3. In this graph, thehorizontal axis represents the rotation angle β, and the vertical axisrepresents the total length L2. Fourier transformation is performed onthe data constellation. By the Fourier transformation, a frequencyspectrum is obtained. In other words, by the Fourier transformation, acoefficient of a Fourier series represented by the following formula isobtained.

$F_{k} = {\sum\limits_{n = 0}^{N - 1}\left( {{a_{n}\cos \; 2\pi \frac{nk}{N}} + {b_{n}\sin \; 2\pi \frac{nk}{N}}} \right)}$

The above mathematical formula is a combination of two trigonometricfunctions having different periods. In the above mathematical formula,a_(n) and b_(n) are Fourier coefficients. The magnitude of eachcomponent to be combined is determined depending on these Fouriercoefficients. Each coefficient is represented by the followingmathematical formula.

$a_{n} = {\frac{1}{N}{\sum\limits_{k = 0}^{N - 1}{F_{k}\cos \; 2\pi \frac{nk}{N}}}}$$b_{n} = {\frac{1}{N}{\sum\limits_{k = 0}^{N - 1}{F_{k}\sin \; 2\pi \frac{nk}{N}}}}$

In the above mathematical formulas, N is the total number of pieces ofdata of the data constellation, and F_(k) is the kth value in the dataconstellation. The spectrum is represented by the following mathematicalformula.

P _(n)=√{square root over (a _(n) ² +b _(n) ²)}

By the Fourier transformation, a transformed data constellation isobtained. FIG. 10 shows a graph plotting the transformed dataconstellation. In this graph, the horizontal axis represents an order,and the vertical axis represents an amplitude. From this graph, themaximum peak is determined. Furthermore, the peak value Pd1 of themaximum peak and the order Fd1 of the maximum peak are determined. Thepeak value Pd1 and the order Fd1 are numeric values representing theaerodynamic characteristic during rotation about the first axis Ax1. Inthe present embodiment, the peak value Pd1 is 270.2 mm, and the orderFd1 is 33.

FIG. 11 also shows the phantom sphere 14 of the golf ball 2. FIG. 11shows the equator Eq and the longitude line Loa having a longitude ϕ ofzero. In FIG. 11, the point (0, 0) is located in the front. In FIG. 11,reference character Ax2 represents a second axis. The second axis Ax2passes through a point Pn2 and a point Ps2. The point Pn2 and the pointPs2 are present on the surface of the phantom sphere 14. The coordinatesof the point Pn2 are (60, 270). The coordinates of the point Ps2 are(−60, 90). The second axis Ax2 is tilted relative to the earth axis. Theangle of the tilt is 30°.

FIG. 11 shows a second great circle GC2 that is present on the surfaceof the phantom sphere 14 of the golf ball 2 and to which the second axisAx2 is orthogonal. The second great circle GC2 is tilted relative to theequator Eq. The angle of the tilt is 30°.

For rotation about the second axis Ax2, an aerodynamic characteristic isevaluated by the same method as that for rotation about the first axisAx1. Specifically, for rotation about the second axis Ax2, two smallcircles C1 and C2 are assumed. The absolute value of the central anglebetween the small circle C1 and the second great circle GC2 is 30°. Theabsolute value of the central angle between the small circle C2 and thesecond great circle GC2 is also 30°. In the region, of the surface ofthe golf ball 2, sandwiched between these small circles, 1440 totallengths L2 are calculated. In other words, a data constellation for thesecond axis Ax2 is calculated. Fourier transformation is performed onthis data constellation, thereby obtaining a transformed dataconstellation. From a graph plotting the transformed data constellation,the peak value Pd2 of the maximum peak and the order Fd2 of the maximumpeak are determined. The peak value Pd2 and the order Fd2 are numericvalues representing the aerodynamic characteristic during rotation aboutthe second axis Ax2. In the present embodiment, the peak value Pd2 is177.9 mm, and the order Fd2 is 37.

FIG. 12 also shows the phantom sphere 14 of the golf ball 2. FIG. 12shows the equator Eq and the longitude line Loa having a longitude ϕ ofzero. In FIG. 12, the point (0, 0) is located in the front. In FIG. 12,reference character Ax3 represents a third axis. The third axis Ax3passes through a point Pn3 and a point Ps3. The point Pn3 and the pointPs3 are present on the surface of the phantom sphere 14. The coordinatesof the point Pn3 are (45, 270). The coordinates of the point Ps3 are(−45, 90). The third axis Ax3 is tilted relative to the earth axis. Theangle of the tilt is 45°.

FIG. 12 shows a third great circle GC3 that is present on the surface ofthe phantom sphere 14 of the golf ball 2 and to which the third axis Ax3is orthogonal. The third great circle GC3 is tilted relative to theequator Eq. The angle of the tilt is 45°.

For rotation about the third axis Ax3, an aerodynamic characteristic isevaluated by the same method as that for rotation about the first axisAx1. Specifically, for rotation about the third axis Ax3, two smallcircles C1 and C2 are assumed. The absolute value of the central anglebetween the small circle C1 and the third great circle GC3 is 30°. Theabsolute value of the central angle between the small circle C2 and thethird great circle GC3 is also 30°. In the region, of the surface of thegolf ball 2, sandwiched between these small circles, 1440 total lengthsL2 are calculated. In other words, a data constellation for the thirdaxis Ax3 is calculated. Fourier transformation is performed on this dataconstellation, thereby obtaining a transformed data constellation. Froma graph plotting the transformed data constellation, the peak value Pd3of the maximum peak and the order Fd3 of the maximum peak aredetermined. The peak value Pd3 and the order Fd3 are numeric valuesrepresenting the aerodynamic characteristic during rotation about thethird axis Ax3. In the present embodiment, the peak value Pd3 is 150.2mm, and the order Fd3 is 37.

FIG. 13 also shows the phantom sphere 14 of the golf ball 2. FIG. 13shows the equator Eq and the longitude line Loa having a longitude ϕ ofzero. In FIG. 13, the point (0, 0) is located in the front. In FIG. 13,reference character Ax4 represents a fourth axis. The fourth axis Ax4passes through a point Pn4 and a point Ps4. The point Pn4 and the pointPs4 are present on the surface of the phantom sphere 14. The coordinatesof the point Pn4 are (30, 270). The coordinates of the point Ps4 are(−30, 90). The fourth axis Ax4 is tilted relative to the earth axis. Theangle of the tilt is 60°.

FIG. 13 shows a fourth great circle GC4 that is present on the surfaceof the phantom sphere 14 of the golf ball 2 and to which the fourth axisAx4 is orthogonal. The fourth great circle GC4 is tilted relative to theequator Eq. The angle of the tilt is 60°.

For rotation about the fourth axis Ax4, an aerodynamic characteristic isevaluated by the same method as that for rotation about the first axisAx1. Specifically, for rotation about the fourth axis Ax4, two smallcircles C1 and C2 are assumed. The absolute value of the central anglebetween the small circle C1 and the fourth great circle GC4 is 30°. Theabsolute value of the central angle between the small circle C2 and thefourth great circle GC4 is also 30°. In the region, of the surface ofthe golf ball 2, sandwiched between these small circles, 1440 totallengths L2 are calculated. In other words, a data constellation for thefourth axis Ax4 is calculated. Fourier transformation is performed onthis data constellation, thereby obtaining a transformed dataconstellation. From a graph plotting the transformed data constellation,the peak value Pd4 of the maximum peak and the order Fd4 of the maximumpeak are determined. The peak value Pd4 and the order Fd4 are numericvalues representing the aerodynamic characteristic during rotation aboutthe fourth axis Ax4. In the present embodiment, the peak value Pd4 is316.4 mm, and the order Fd4 is 34.

FIG. 14 also shows the phantom sphere 14 of the golf ball 2. FIG. 14shows the equator Eq and the longitude line Loa having a longitude ϕ ofzero. In FIG. 14, the point (0, 0) is located in the front. In FIG. 14,reference character Ax5 represents a fifth axis. The fifth axis Ax5passes through a point Pn5 and a point Ps5. The point Pn5 and the pointPs5 are present on the surface of the phantom sphere 14. The coordinatesof the point Pn5 are (15, 270). The coordinates of the point Ps5 are(−15, 90). The fifth axis Ax5 is tilted relative to the earth axis. Theangle of the tilt is 75°.

FIG. 14 shows a fifth great circle GC5 that is present on the surface ofthe phantom sphere 14 of the golf ball 2 and to which the fifth axis Ax5is orthogonal. The fifth great circle GC5 is tilted relative to theequator Eq. The angle of the tilt is 75°.

For rotation about the fifth axis Ax5, an aerodynamic characteristic isevaluated by the same method as that for rotation about the first axisAx1. Specifically, for rotation about the fifth axis Ax5, two smallcircles C1 and C2 are assumed. The absolute value of the central anglebetween the small circle C1 and the fifth great circle GC5 is 30°. Theabsolute value of the central angle between the small circle C2 and thefifth great circle GC5 is also 30°. In the region, of the surface of thegolf ball 2, sandwiched between these small circles, 1440 total lengthsL2 are calculated. In other words, a data constellation for the fifthaxis Ax5 is calculated. Fourier transformation is performed on this dataconstellation, thereby obtaining a transformed data constellation. Froma graph plotting the transformed data constellation, the peak value Pd5of the maximum peak and the order Fd5 of the maximum peak aredetermined. The peak value Pd5 and the order Fd5 are numeric valuesrepresenting the aerodynamic characteristic during rotation about thefifth axis Ax5. In the present embodiment, the peak value Pd5 is 190.0mm, and the order Fd5 is 27.

FIG. 15 also shows the phantom sphere 14 of the golf ball 2. FIG. 15shows the equator Eq and a longitude line Lob having a longitude ϕ of90°. In FIG. 15, a point (0, 90) is located in the front. In FIG. 15,reference character Ax6 represents a sixth axis. The sixth axis Ax6passes through a point Pn6 and a point Ps6. The point Pn6 and the pointPs6 are present on the surface of the phantom sphere 14. The coordinatesof the point Pn6 are (75, 0). The coordinates of the point Ps6 are (−75,180). The sixth axis Ax6 is tilted relative to the earth axis. The angleof the tilt is 15°.

FIG. 15 shows a sixth great circle GC6 that is present on the surface ofthe phantom sphere 14 of the golf ball 2 and to which the sixth axis Ax6is orthogonal. The sixth great circle GC6 is tilted relative to theequator Eq. The angle of the tilt is 15°.

For rotation about the sixth axis Ax6, an aerodynamic characteristic isevaluated by the same method as that for rotation about the first axisAx1. Specifically, for rotation about the sixth axis Ax6, two smallcircles C1 and C2 are assumed. The absolute value of the central anglebetween the small circle C1 and the sixth great circle GC6 is 30°. Theabsolute value of the central angle between the small circle C2 and thesixth great circle GC6 is also 30°. In the region, of the surface of thegolf ball 2, sandwiched between these small circles, 1440 total lengthsL2 are calculated. In other words, a data constellation for the sixthaxis Ax6 is calculated. Fourier transformation is performed on this dataconstellation, thereby obtaining a transformed data constellation. Froma graph plotting the transformed data constellation, the peak value Pd6of the maximum peak and the order Fd6 of the maximum peak aredetermined. The peak value Pd6 and the order Fd6 are numeric valuesrepresenting the aerodynamic characteristic during rotation about thesixth axis Ax6. In the present embodiment, the peak value Pd6 is 270.2mm, and the order Fd6 is 33.

FIG. 16 also shows the phantom sphere 14 of the golf ball 2. FIG. 16shows the equator Eq and the longitude line Lob having a longitude ϕ of90°. In FIG. 16, the point (0, 90) is located in the front. In FIG. 16,reference character Ax7 represents a seventh axis. The seventh axis Ax7passes through a point Pn7 and a point Ps7. The point Pn7 and the pointPs7 are present on the surface of the phantom sphere 14. The coordinatesof the point Pn7 are (60, 0). The coordinates of the point Ps7 are (−60,180). The seventh axis Ax7 is tilted relative to the earth axis. Theangle of the tilt is 30°.

FIG. 16 shows a seventh great circle GC7 that is present on the surfaceof the phantom sphere 14 of the golf ball 2 and to which the seventhaxis Ax7 is orthogonal. The seventh great circle GC7 is tilted relativeto the equator Eq. The angle of the tilt is 30°.

For rotation about the seventh axis Ax7, an aerodynamic characteristicis evaluated by the same method as that for rotation about the firstaxis Ax1. Specifically, for rotation about the seventh axis Ax7, twosmall circles C1 and C2 are assumed. The absolute value of the centralangle between the small circle C1 and the seventh great circle GC7 is30°. The absolute value of the central angle between the small circle C2and the seventh great circle GC7 is also 30°. In the region, of thesurface of the golf ball 2, sandwiched between these small circles, 1440total lengths L2 are calculated. In other words, a data constellationfor the seventh axis Ax7 is calculated. Fourier transformation isperformed on this data constellation, thereby obtaining a transformeddata constellation. From a graph plotting the transformed dataconstellation, the peak value Pd7 of the maximum peak and the order Fd7of the maximum peak are determined. The peak value Pd7 and the order Fd7are numeric values representing the aerodynamic characteristic duringrotation about the seventh axis Ax1. In the present embodiment, the peakvalue Pd7 is 177.9 mm, and the order Fd7 is 37.

FIG. 17 also shows the phantom sphere 14 of the golf ball 2. FIG. 17shows the equator Eq and the longitude line Lob having a longitude ϕ of90°. In FIG. 17, the point (0, 90) is located in the front. In FIG. 17,reference character Ax8 represents an eighth axis. The eighth axis Ax8passes through a point Pn8 and a point Ps8. The point Pn8 and the pointPs8 are present on the surface of the phantom sphere 14. The coordinatesof the point Pn8 are (45, 0). The coordinates of the point Ps8 are (−45,180). The eighth axis Ax8 is tilted relative to the earth axis. Theangle of the tilt is 45°.

FIG. 17 shows an eighth great circle GC8 that is present on the surfaceof the phantom sphere 14 of the golf ball 2 and to which the eighth axisAx8 is orthogonal. The eighth great circle GC8 is tilted relative to theequator Eq. The angle of the tilt is 45°.

For rotation about the eighth axis Ax8, an aerodynamic characteristic isevaluated by the same method as that for rotation about the first axisAx1. Specifically, for rotation about the eighth axis Ax8, two smallcircles C1 and C2 are assumed. The absolute value of the central anglebetween the small circle C1 and the eighth great circle GC8 is 30°. Theabsolute value of the central angle between the small circle C2 and theeighth great circle GC8 is also 30°. In the region, of the surface ofthe golf ball 2, sandwiched between these small circles, 1440 totallengths L2 are calculated. In other words, a data constellation for theeighth axis Ax8 is calculated. Fourier transformation is performed onthis data constellation, thereby obtaining a transformed dataconstellation. From a graph plotting the transformed data constellation,the peak value Pd8 of the maximum peak and the order Fd8 of the maximumpeak are determined. The peak value Pd8 and the order Fd8 are numericvalues representing the aerodynamic characteristic during rotation aboutthe eighth axis Ax8. In the present embodiment, the peak value Pd8 is150.2 mm, and the order Fd8 is 37.

FIG. 18 also shows the phantom sphere 14 of the golf ball 2. FIG. 18shows the equator Eq and the longitude line Lob having a longitude ϕ of90°. In FIG. 18, the point (0, 90) is located in the front. In FIG. 18,reference character Ax9 represents a ninth axis. The ninth axis Ax9passes through a point Pn9 and a point Ps9. The point Pn9 and the pointPs9 are present on the surface of the phantom sphere 14. The coordinatesof the point Pn9 are (30, 0). The coordinates of the point Ps9 are (−30,180). The ninth axis Ax9 is tilted relative to the earth axis. The angleof the tilt is 60°.

FIG. 18 shows a ninth great circle GC9 that is present on the surface ofthe phantom sphere 14 of the golf ball 2 and to which the ninth axis Ax9is orthogonal. The ninth great circle GC9 is tilted relative to theequator Eq. The angle of the tilt is 60°.

For rotation about the ninth axis Ax9, an aerodynamic characteristic isevaluated by the same method as that for rotation about the first axisAx1. Specifically, for rotation about the ninth axis Ax9, two smallcircles C1 and C2 are assumed. The absolute value of the central anglebetween the small circle C1 and the ninth great circle GC9 is 30°. Theabsolute value of the central angle between the small circle C2 and theninth great circle GC9 is also 30°. In the region, of the surface of thegolf ball 2, sandwiched between these small circles, 1440 total lengthsL2 are calculated. In other words, a data constellation for the ninthaxis Ax9 is calculated. Fourier transformation is performed on this dataconstellation, thereby obtaining a transformed data constellation. Froma graph plotting the transformed data constellation, the peak value Pd9of the maximum peak and the order Fd9 of the maximum peak aredetermined. The peak value Pd9 and the order Fd9 are numeric valuesrepresenting the aerodynamic characteristic during rotation about theninth axis Ax9. In the present embodiment, the peak value Pd9 is 316.4mm, and the order Fd9 is 34.

FIG. 19 also shows the phantom sphere 14 of the golf ball 2. FIG. 19shows the equator Eq and the longitude line Lob having a longitude ϕ of90°. In FIG. 19, the point (0, 90) is located in the front. In FIG. 19,reference character Ax10 represents a tenth axis. The tenth axis Ax10passes through a point Pn10 and a point Ps10. The point Pn10 and thepoint Ps10 are present on the surface of the phantom sphere 14. Thecoordinates of the point Pn10 are (15, 0). The coordinates of the pointPs10 are (−15, 180). The tenth axis Ax10 is tilted relative to the earthaxis. The angle of the tilt is 75°.

FIG. 19 shows a tenth great circle GC10 that is present on the surfaceof the phantom sphere 14 of the golf ball 2 and to which the tenth axisAx10 is orthogonal. The tenth great circle GC10 is tilted relative tothe equator Eq. The angle of the tilt is 75°.

For rotation about the tenth axis Ax10, an aerodynamic characteristic isevaluated by the same method as that for rotation about the first axisAx1. Specifically, for rotation about the tenth axis Ax10, two smallcircles C1 and C2 are assumed. The absolute value of the central anglebetween the small circle C1 and the tenth great circle GC10 is 30°. Theabsolute value of the central angle between the small circle C2 and thetenth great circle GC10 is also 30°. In the region, of the surface ofthe golf ball 2, sandwiched between these small circles, 1440 totallengths L2 are calculated. In other words, a data constellation for thetenth axis Ax10 is calculated. Fourier transformation is performed onthis data constellation, thereby obtaining a transformed dataconstellation. From a graph plotting the transformed data constellation,the peak value Pd10 of the maximum peak and the order Fd10 of themaximum peak are determined. The peak value Pd10 and the order Fd10 arenumeric values representing the aerodynamic characteristic duringrotation about the tenth axis Ax10. In the present embodiment, the peakvalue Pd10 is 190.0 mm, and the order Fd10 is 27.

FIG. 20 also shows the phantom sphere 14 of the golf ball 2. FIG. 20shows the equator Eq and a longitude line Loc having a longitude ϕ of180°. In FIG. 20, a point (0, 180) is located in the front. In FIG. 20,reference character Ax11 represents an eleventh axis. The eleventh axisAx11 passes through a point Pn11 and a point Ps11. The point Pn11 andthe point Ps11 are present on the surface of the phantom sphere 14. Thecoordinates of the point Pn11 are (75, 90). The coordinates of the pointPs11 are (−75, 270). The eleventh axis Ax11 is tilted relative to theearth axis. The angle of the tilt is 15°.

FIG. 20 shows an eleventh great circle GC11 that is present on thesurface of the phantom sphere 14 of the golf ball 2 and to which theeleventh axis Ax11 is orthogonal. The eleventh great circle GC11 istilted relative to the equator Eq. The angle of the tilt is 15°.

For rotation about the eleventh axis Ax11, an aerodynamic characteristicis evaluated by the same method as that for rotation about the firstaxis Ax1. Specifically, for rotation about the eleventh axis Ax11, twosmall circles C1 and C2 are assumed. The absolute value of the centralangle between the small circle C1 and the eleventh great circle GC11 is30°. The absolute value of the central angle between the small circle C2and the eleventh great circle GC11 is also 30°. In the region, of thesurface of the golf ball 2, sandwiched between these small circles, 1440total lengths L2 are calculated. In other words, a data constellationfor the eleventh axis Ax11 is calculated. Fourier transformation isperformed on this data constellation, thereby obtaining a transformeddata constellation. From a graph plotting the transformed dataconstellation, the peak value Pd11 of the maximum peak and the orderFd11 of the maximum peak are determined. The peak value Pd11 and theorder Fd11 are numeric values representing the aerodynamiccharacteristic during rotation about the eleventh axis Ax11. In thepresent embodiment, the peak value Pd11 is 270.2 mm, and the order Fd11is 33.

FIG. 21 also shows the phantom sphere 14 of the golf ball 2. FIG. 21shows the equator Eq and the longitude line Loc having a longitude ϕ of180°. In FIG. 21, the point (0, 180) is located in the front. In FIG.21, reference character Ax12 represents a twelfth axis. The twelfth axisAx12 passes through a point Pn12 and a point Ps12. The point Pn12 andthe point Ps12 are present on the surface of the phantom sphere 14. Thecoordinates of the point Pn12 are (60, 90). The coordinates of the pointPs12 are (−60, 270). The twelfth axis Ax12 is tilted relative to theearth axis. The angle of the tilt is 30°.

FIG. 21 shows a twelfth great circle GC12 that is present on the surfaceof the phantom sphere 14 of the golf ball 2 and to which the twelfthaxis Ax12 is orthogonal. The twelfth great circle GC12 is tiltedrelative to the equator Eq. The angle of the tilt is 30°.

For rotation about the twelfth axis Ax12, an aerodynamic characteristicis evaluated by the same method as that for rotation about the firstaxis Ax1. Specifically, for rotation about the twelfth axis Ax12, twosmall circles C1 and C2 are assumed. The absolute value of the centralangle between the small circle C1 and the twelfth great circle GC12 is30°. The absolute value of the central angle between the small circle C2and the twelfth great circle GC12 is also 30°. In the region, of thesurface of the golf ball 2, sandwiched between these small circles, 1440total lengths L2 are calculated. In other words, a data constellationfor the twelfth axis Ax12 is calculated. Fourier transformation isperformed on this data constellation, thereby obtaining a transformeddata constellation. From a graph plotting the transformed dataconstellation, the peak value Pd12 of the maximum peak and the orderFd12 of the maximum peak are determined. The peak value Pd12 and theorder Fd12 are numeric values representing the aerodynamiccharacteristic during rotation about the twelfth axis Ax12. In thepresent embodiment, the peak value Pd12 is 177.9 mm, and the order Fd12is 37.

FIG. 22 also shows the phantom sphere 14 of the golf ball 2. FIG. 22shows the equator Eq and the longitude line Loc having a longitude ϕ of180°. In FIG. 22, the point (0, 180) is located in the front. In FIG.22, reference character Ax13 represents a thirteenth axis. Thethirteenth axis Ax13 passes through a point Pn13 and a point Ps13. Thepoint Pn13 and the point Ps13 are present on the surface of the phantomsphere 14. The coordinates of the point Pn13 are (45, 90). Thecoordinates of the point Ps13 are (−45, 270). The thirteenth axis Ax13is tilted relative to the earth axis. The angle of the tilt is 45°.

FIG. 22 shows a thirteenth great circle GC13 that is present on thesurface of the phantom sphere 14 of the golf ball 2 and to which thethirteenth axis Ax13 is orthogonal. The thirteenth great circle GC13 istilted relative to the equator Eq. The angle of the tilt is 45°.

For rotation about the thirteenth axis Ax13, an aerodynamiccharacteristic is evaluated by the same method as that for rotationabout the first axis Ax1. Specifically, for rotation about thethirteenth axis Ax13, two small circles C1 and C2 are assumed. Theabsolute value of the central angle between the small circle C1 and thethirteenth great circle GC13 is 30°. The absolute value of the centralangle between the small circle C2 and the thirteenth great circle GC13is also 30°. In the region, of the surface of the golf ball 2,sandwiched between these small circles, 1440 total lengths L2 arecalculated. In other words, a data constellation for the thirteenth axisAx13 is calculated. Fourier transformation is performed on this dataconstellation, thereby obtaining a transformed data constellation. Froma graph plotting the transformed data constellation, the peak value Pd13of the maximum peak and the order Fd13 of the maximum peak aredetermined. The peak value Pd13 and the order Fd13 are numeric valuesrepresenting the aerodynamic characteristic during rotation about thethirteenth axis Ax13. In the present embodiment, the peak value Pd13 is150.2 mm, and the order Fd13 is 37.

FIG. 23 also shows the phantom sphere 14 of the golf ball 2. FIG. 23shows the equator Eq and the longitude line Loc having a longitude ϕ of180°. In FIG. 23, the point (0, 180) is located in the front. In FIG.23, reference character Ax14 represents a fourteenth axis. Thefourteenth axis Ax14 passes through a point Pn14 and a point Ps14. Thepoint Pn14 and the point Ps14 are present on the surface of the phantomsphere 14. The coordinates of the point Pn14 are (30, 90). Thecoordinates of the point Ps14 are (−30, 270). The fourteenth axis Ax14is tilted relative to the earth axis. The angle of the tilt is 60°.

FIG. 23 shows a fourteenth great circle GC14 that is present on thesurface of the phantom sphere 14 of the golf ball 2 and to which thefourteenth axis Ax14 is orthogonal. The fourteenth great circle GC14 istilted relative to the equator Eq. The angle of the tilt is 60°.

For rotation about the fourteenth axis Ax14, an aerodynamiccharacteristic is evaluated by the same method as that for rotationabout the first axis Ax1. Specifically, for rotation about thefourteenth axis Ax14, two small circles C1 and C2 are assumed. Theabsolute value of the central angle between the small circle C1 and thefourteenth great circle GC14 is 30°. The absolute value of the centralangle between the small circle C2 and the fourteenth great circle GC14is also 30°. In the region, of the surface of the golf ball 2,sandwiched between these small circles, 1440 total lengths L2 arecalculated. In other words, a data constellation for the fourteenth axisAx14 is calculated. Fourier transformation is performed on this dataconstellation, thereby obtaining a transformed data constellation. Froma graph plotting the transformed data constellation, the peak value Pd14of the maximum peak and the order Fd14 of the maximum peak aredetermined. The peak value Pd14 and the order Fd14 are numeric valuesrepresenting the aerodynamic characteristic during rotation about thefourteenth axis Ax14. In the present embodiment, the peak value Pd14 is316.4 mm, and the order Fd14 is 34.

FIG. 24 also shows the phantom sphere 14 of the golf ball 2. FIG. 24shows the equator Eq and the longitude line Loc having a longitude ϕ of180°. In FIG. 24, the point (0, 180) is located in the front. In FIG.24, reference character Ax15 represents a fifteenth axis. The fifteenthaxis Ax15 passes through a point Pn15 and a point Ps15. The point Pn15and the point Ps15 are present on the surface of the phantom sphere 14.The coordinates of the point Pn15 are (15, 90). The coordinates of thepoint Ps15 are (−15, 270). The fifteenth axis Ax15 is tilted relative tothe earth axis. The angle of the tilt is 75°.

FIG. 24 shows a fifteenth great circle GC15 that is present on thesurface of the phantom sphere 14 of the golf ball 2 and to which thefifteenth axis Ax15 is orthogonal. The fifteenth great circle GC15 istilted relative to the equator Eq. The angle of the tilt is 75°.

For rotation about the fifteenth axis Ax15, an aerodynamiccharacteristic is evaluated by the same method as that for rotationabout the first axis Ax1. Specifically, for rotation about the fifteenthaxis Ax15, two small circles C1 and C2 are assumed. The absolute valueof the central angle between the small circle C1 and the fifteenth greatcircle GC15 is 30°. The absolute value of the central angle between thesmall circle C2 and the fifteenth great circle GC15 is also 30°. In theregion, of the surface of the golf ball 2, sandwiched between thesesmall circles, 1440 total lengths L2 are calculated. In other words, adata constellation for the fifteenth axis Ax15 is calculated. Fouriertransformation is performed on this data constellation, therebyobtaining a transformed data constellation. From a graph plotting thetransformed data constellation, the peak value Pd15 of the maximum peakand the order Fd15 of the maximum peak are determined. The peak valuePd15 and the order Fd15 are numeric values representing the aerodynamiccharacteristic during rotation about the fifteenth axis Ax15. In thepresent embodiment, the peak value Pd15 is 190.0 mm, and the order Fd15is 27.

In this evaluation method, the steps (a) to (h) are executed for each of15 axes Ax that are

(1) the first axis Ax1 passing through the point Pn1 the coordinates ofwhich are (75, 270) and the point Ps1 the coordinates of which are (−75,90),

(2) the second axis Ax2 passing through the point Pn2 the coordinates ofwhich are (60, 270) and the point Ps2 the coordinates of which are (−60,90),

(3) the third axis Ax3 passing through the point Pn3 the coordinates ofwhich are (45, 270) and the point Ps3 the coordinates of which are (−45,90),

(4) the fourth axis Ax4 passing through the point Pn4 the coordinates ofwhich are (30, 270) and the point Ps4 the coordinates of which are (−30,90),

(5) the fifth axis Ax5 passing through the point Pn5 the coordinates ofwhich are (15, 270) and the point Ps5 the coordinates of which are (−15,90),

(6) the sixth axis Ax6 passing through the point Pn6 the coordinates ofwhich are (75, 0) and the point Ps6 the coordinates of which are (−75,180),

(7) the seventh axis Ax1 passing through the point Pn7 the coordinatesof which are (60, 0) and the point Ps7 the coordinates of which are(−60, 180),

(8) the eighth axis Ax8 passing through the point Pn8 the coordinates ofwhich are (45, 0) and the point Ps8 the coordinates of which are (−45,180),

(9) the ninth axis Ax9 passing through the point Pn9 the coordinates ofwhich are (30, 0) and the point Ps9 the coordinates of which are (−30,180),

(10) the tenth axis Ax10 passing through the point Pn10 the coordinatesof which are (15, 0) and the point Ps10 the coordinates of which are(−15, 180),

(11) the eleventh axis Ax11 passing through the point Pn11 thecoordinates of which are (75, 90) and the point Ps11 the coordinates ofwhich are (−75, 270),

(12) the twelfth axis Ax12 passing through the point Pn12 thecoordinates of which are (60, 90) and the point Ps12 the coordinates ofwhich are (−60, 270),

(13) the thirteenth axis Ax13 passing through the point Pn13 thecoordinates of which are (45, 90) and the point Ps13 the coordinates ofwhich are (−45, 270),

(14) the fourteenth axis Ax14 passing through the point Pn14 thecoordinates of which are (30, 90) and the point Ps14 the coordinates ofwhich are (−30, 270), and

(15) the fifteenth axis Ax15 passing through the point Pn15 thecoordinates of which are (15, 90) and the point Ps15 the coordinates ofwhich are (−15, 270). Accordingly, 15 peak values (Pd1 to Pd15) and 15orders (Fd1 to Fd15) are calculated.

The minimums among the 15 peak values (Pd1 to Pd15) are Pd3, Pd8, andPd13. The minimum value of the peak value Pd is 150.2 mm. According tothe findings by the present inventor, the minimum value is preferablynot less than 95 mm. In the golf ball 2 in which the minimum value isnot less than 95 mm, a sufficient dimple effect can be achieved evenduring rotation about any axis Ax. The flight distance of the golf ball2 is large. In this respect, the minimum value of the peak value Pd ismore preferably not less than 120 mm and particularly preferably notless than 140 mm.

The maximums among the 15 peak values (Pd1 to Pd15) are Pd4, Pd9, andPd14. The maximum value of the peak value Pd is 316.4 mm. According tothe findings by the present inventor, the maximum value is preferablynot greater than 500 mm. The golf ball 2 in which the maximum value isnot greater than 500 mm has an excellent aerodynamic characteristic. Theflight distance of the golf ball 2 is large. In this respect, themaximum value of the peak value Pd is more preferably not greater than400 mm and particularly preferably not greater than 330 mm.

The average of the 15 peak values (Pd1 to Pd15) is preferably not lessthan 200 mm. The golf ball 2 in which the average is not less than 200mm has an excellent aerodynamic characteristic. The flight distance ofthe golf ball 2 is large. In this respect, the average is morepreferably not less than 210 mm and particularly preferably not lessthan 220 mm. The average is preferably not greater than 300 mm andparticularly preferably not greater than 230 mm. In the presentembodiment, the average is 220.9 mm.

The minimums among the 15 orders (Fd1 to Fd15) are Fd5, Fd10, and Fd15.The minimum value of the order Fd is 27. According to the findings bythe present inventor, the minimum value is preferably not less than 27.The golf ball 2 in which the minimum value is not less than 27 has anexcellent aerodynamic characteristic. The flight distance of the golfball 2 is large.

The maximums among the 15 orders (Fd1 to Fd15) are Fd2, Fd3, Fd7, Fd8,Fd12, and Fd13. The maximum value of the order Fd is 37. According tothe findings by the present inventor, the maximum value is preferablynot greater than 37. The golf ball 2 in which the maximum value is notgreater than 37 has an excellent aerodynamic characteristic. The flightdistance of the golf ball 2 is large.

The average of the 15 orders (Fd1 to Fd15) is preferably not less than30 and not greater than 34. The golf ball 2 in which the average fallswithin this range has an excellent aerodynamic characteristic. Theflight distance of the golf ball 2 is large. In the present embodiment,the average is 33.6.

In this method, the golf ball 2 is evaluated by the 15 peak values Pdand the 15 orders Fd based on the 15 axes Ax. By this method, theaerodynamic characteristic of the golf ball 2 can be objectivelyevaluated.

EXAMPLES Example 1

A rubber composition was obtained by kneading 100 parts by weight of ahigh-cis polybutadiene (trade name “BR-730”, manufactured by JSRCorporation), 22.5 parts by weight of zinc diacrylate, 5 parts by weightof zinc oxide, 5 parts by weight of barium sulfate, 0.5 parts by weightof diphenyl disulfide, and 0.6 parts by weight of dicumyl peroxide. Thisrubber composition was placed into a mold including upper and lower moldhalves each having a hemispherical cavity, and heated at 170° C. for 18minutes to obtain a core with a diameter of 38.5 mm.

A resin composition was obtained by kneading 50 parts by weight of anionomer resin (trade name “Himilan 1605”, manufactured by Du Pont-MITSUIPOLYCHEMICALS Co., Ltd.), 50 parts by weight of another ionomer resin(trade name “Himilan AM7329”, manufactured by Du Pont-MITSUIPOLYCHEMICALS Co., Ltd.), and 4 parts by weight of titanium dioxide witha twin-screw kneading extruder. The core was covered with this resincomposition by injection molding to form a mid layer with a thickness of1.6 mm.

A paint composition (trade name “POLIN 750LE”, manufactured by SHINTOPAINT CO., LTD.) including a two-component curing type epoxy resin as abase polymer was prepared. The base material liquid of this paintcomposition includes 30 parts by weight of a bisphenol A type solidepoxy resin and 70 parts by weight of a solvent. The curing agent liquidof this paint composition includes 40 parts by weight of a modifiedpolyamide amine, 55 parts by weight of a solvent, and 5 parts by weightof titanium dioxide. The weight ratio of the base material liquid to thecuring agent liquid is 1/1. This paint composition was applied to thesurface of the mid layer with a spray gun, and kept at 23° C. for 6hours to obtain a reinforcing layer with a thickness of 10 μm.

A resin composition was obtained by kneading 100 parts by weight of athermoplastic polyurethane elastomer (trade name “Elastollan XNY85A”,manufactured by BASF Japan Ltd.) and 4 parts by weight of titaniumdioxide with a twin-screw kneading extruder. Half shells were obtainedfrom this resin composition by compression molding. The sphereconsisting of the core, the mid layer, and the reinforcing layer wascovered with two of these half shells. These half shells and the spherewere placed into a final mold that includes upper and lower mold halveseach having a hemispherical cavity and having a large number of pimpleson its cavity face, and a cover was obtained by compression molding. Thethickness of the cover was 0.5 mm. Dimples having a shape that is theinverted shape of the pimples were formed on the cover. A clear paintincluding a two-component curing type polyurethane as a base materialwas applied to this cover to obtain a golf ball of Example 1 with adiameter of about 42.7 mm and a weight of about 45.6 g. The dimplepattern of the golf ball is shown in FIGS. 2 and 3. The specificationsof the dimples of the golf ball are shown in Table 1 below. The peakvalues (Pd1 to Pd15) and the orders (Fd1 to Fd15) of the golf ball areshown in Table 3 below.

Examples 2 and 3 and Comparative Examples 1 to 4

Golf balls of Examples 2 and 3 and Comparative Examples 1 to 4 wereobtained in the same manner as Example 1, except the specifications ofthe dimples were as shown in Tables 1 and 2 below. The peak values (Pd1to Pd15) and the orders (Fd1 to Fd15) of each golf ball are shown inTable 3 or 4 below.

[Flight Test]

A driver with a head made of a titanium alloy (trade name “SRIXON Z-TX”,manufactured by DUNLOP SPORTS CO. LTD., shaft hardness: X, loft angle:8.5°) was attached to a swing machine manufactured by Golf Laboratories,Inc. A golf ball was put on a tee. The golf ball was hit under theconditions of a head speed of 50 m/sec, a launch angle of about 10°, anda backspin rate of about 2500 rpm, and the distance from the launchpoint to the stop point was measured. During the test, the weather wasalmost windless. The average value of data obtained by 100 measurementsis shown in Tables 5 and 6 below. The orientation of the golf ball whenthe golf ball was put on the tee was randomly determined. Therefore, theaxis for the backspin was randomly selected.

TABLE 1 Specifications of Dimples Dm Dp2 Dp1 CR V Number (mm) (mm) (mm)(mm) (mm³) Ex. A 60 4.40 0.138 0.2506 17.61 1.051 1 B 158 4.30 0.1370.2445 16.94 0.996 C 72 4.15 0.134 0.2341 16.13 0.908 D 36 3.90 0.1230.2114 15.52 0.736 E 12 3.00 0.122 0.1743 9.28 0.432 Ex. A 30 4.60 0.1350.2581 19.66 1.123 2 B 66 4.50 0.135 0.2528 18.82 1.075 C 84 4.40 0.1350.2476 17.99 1.028 D 30 4.30 0.135 0.2425 17.19 0.982 E 48 4.20 0.1350.2376 16.40 0.936 F 60 4.00 0.135 0.2280 14.88 0.850 G 6 2.70 0.1350.1773 6.82 0.388 Ex. A 6 4.70 0.135 0.2635 20.52 1.172 3 B 126 4.400.135 0.2476 17.99 1.028 C 122 4.30 0.135 0.2425 17.19 0.982 D 6 4.150.135 0.2351 16.01 0.914 E 66 3.90 0.135 0.2234 14.15 0.808 F 12 3.000.135 0.1873 8.40 0.478

TABLE 2 Specifications of Dimples Dm Dp2 Dp1 CR V Number (mm) (mm) (mm)(mm) (mm³) Com. A 30 4.60 0.135 0.2581 19.66 1.123 Ex. B 68 4.50 0.1350.2528 18.82 1.075 1 C 92 4.40 0.135 0.2476 17.99 1.028 D 74 4.30 0.1350.2425 17.19 0.982 E 38 4.15 0.135 0.2351 16.01 0.914 F 14 3.85 0.1350.2211 13.79 0.787 G 8 3.60 0.135 0.2103 12.07 0.688 Com. A 156 4.910.135 0.2766 22.39 2.609 Ex. B 98 4.65 0.135 0.2620 20.09 2.217 2 C 123.00 0.135 0.1878 8.40 0.663 Com. A 70 4.10 0.135 0.2336 15.63 1.538 Ex.B 30 3.90 0.135 0.2242 14.15 1.336 3 C 120 3.80 0.135 0.2197 13.44 1.243D 170 3.70 0.135 0.2153 12.74 1.155 E 20 3.60 0.135 0.2110 12.07 1.072 F12 2.50 0.135 0.1716 5.85 0.422 Com. A 30 4.60 0.135 0.2581 19.66 1.123Ex. B 54 4.50 0.135 0.2528 18.82 1.075 4 C 72 4.30 0.135 0.2425 17.190.982 D 54 4.20 0.135 0.2376 16.40 0.936 E 108 4.00 0.135 0.2280 14.880.850 F 12 2.70 0.135 0.1773 6.82 0.388

TABLE 3 Aerodynamic Characteristic Example 1 Example 2 Example 3 PeakPd1 270.2 143.5 195.1 value Pd2 177.9 195.4 153.1 Pd3 150.2 147.0 147.8Pd4 316.4 322.0 322.0 Pd5 190.0 152.2 152.2 Pd6 270.2 143.5 195.1 Pd7177.9 195.4 153.1 Pd8 150.2 147.0 147.8 Pd9 316.4 322.0 322.0 Pd10 190.0152.2 152.2 Pd11 270.2 143.5 195.1 Pd12 177.9 195.4 153.1 Pd13 150.2147.0 147.8 Pd14 316.4 322.0 322.0 Pd15 190.0 152.2 152.2 Order Fd1 3331 31 Fd2 37 31 31 Fd3 37 33 33 Fd4 34 36 36 Fd5 27 29 29 Fd6 33 31 31Fd7 37 31 31 Fd8 37 33 33 Fd9 34 36 36 Fd10 27 29 29 Fd11 33 31 31 Fd1237 31 31 Fd13 37 33 33 Fd14 34 36 36 Fd15 27 29 29

TABLE 4 Aerodynamic Characteristic Compa. Compa. Compa. Compa. Example 1Example 2 Example 3 Example 4 Peak Pd1 116.0 245.2 181.3 206.0 value Pd293.2 204.6 117.2 302.6 Pd3 174.6 317.5 87.3 190.4 Pd4 440.9 336.5 296.0420.1 Pd5 151.1 134.7 146.3 112.6 Pd6 207.7 147.7 225.3 196.5 Pd7 177.0230.7 329.8 155.2 Pd8 165.9 458.1 347.1 281.5 Pd9 257.7 778.5 259.2358.3 Pd10 157.5 244.8 165.7 89.7 Pd11 187.0 524.8 181.3 206.0 Pd12146.3 284.0 117.2 302.6 Pd13 263.3 184.0 87.3 190.4 Pd14 383.1 282.7296.0 420.1 Pd15 146.1 185.4 146.3 112.6 Order Fd1 31 25 35 31 Fd2 33 2937 33 Fd3 30 29 35 29 Fd4 34 31 41 31 Fd5 32 31 35 29 Fd6 30 33 39 35Fd7 33 31 37 37 Fd8 34 29 39 31 Fd9 34 31 41 33 Fd10 30 29 35 33 Fd11 3129 35 31 Fd12 32 23 37 33 Fd13 32 29 35 29 Fd14 34 31 41 31 Fd15 32 3135 29

TABLE 5 Results of Evaluation Example 1 Example 2 Example 3 Front viewFIG. 2 FIG. 25 FIG. 27 Plan view FIG. 3 FIG. 26 FIG. 28 Total number N338 324 338 Total volume 564.6 579.0 574.3 TV (mm³) Peak value Max 316.4322.0 322.0 Pd Min 150.2 143.5 147.8 Average 220.9 192.0 194.0 Order Max37 36 36 Fd Min 27 29 29 Average 33.6 32.0 32.0 Flight 263.5 262.5 263.0distance (m)

TABLE 6 Results of Evaluation Compa. Compa. Compa. Compa. Example 1Example 2 Example 3 Example 4 Front view FIG. 29 FIG. 31 FIG. 33 FIG. 35Plan view FIG. 30 FIG. 32 FIG. 34 FIG. 36 Total number N 324 266 422 330Total volume 589.7 632.2 519.8 571.3 TV (mm³) Peak value Max 440.9 778.5347.1 420.1 Pd Min 93.2 134.7 87.3 89.7 Average 204.5 304.0 198.9 236.3Order Max 34 33 41 37 Fd Min 30 23 34 29 Average 32.1 29.4 37.1 31.7Flight 261.4 261.2 261.0 261.0 distance (m)

As shown in Tables 5 and 6, the golf ball of each Example has excellentflight performance. From the results of evaluation, advantages of thepresent invention are clear.

The aforementioned dimple pattern is applicable to golf balls havingvarious structures such as a one-piece golf ball, a two-piece golf ball,a four-piece golf ball, a five-piece golf ball, a six-piece golf ball, athread-wound golf ball, and the like in addition to a three-piece golfball. The above descriptions are merely illustrative examples, andvarious modifications can be made without departing from the principlesof the present invention.

What is claimed is:
 1. A golf ball having a plurality of dimples on asurface thereof, wherein a minimum value of 15 peak values obtained byexecuting steps (a) to (h) for each of 15 axes Ax is not less than 95mm, when spherical polar coordinates of a point that is located on asurface of a phantom sphere of the golf ball and has a latitude of θ(degrees) and a longitude of ϕ (degrees) are represented by (θ, ϕ), the15 axes Ax being (1) a first axis Ax1 passing through a point Pn1coordinates of which are (75, 270) and a point Ps1 coordinates of whichare (−75, 90), (2) a second axis Ax2 passing through a point Pn2coordinates of which are (60, 270) and a point Ps2 coordinates of whichare (−60, 90) (3) a third axis Ax3 passing through a point Pn3coordinates of which are (45, 270) and a point Ps3 coordinates of whichare (−45, 90), (4) a fourth axis Ax4 passing through a point Pn4coordinates of which are (30, 270) and a point Ps4 coordinates of whichare (−30, 90), (5) a fifth axis Ax5 passing through a point Pn5coordinates of which are (15, 270) and a point Ps5 coordinates of whichare (−15, 90), (6) a sixth axis Ax6 passing through a point Pn6coordinates of which are (75, 0) and a point Ps6 coordinates of whichare (−75, 180), (7) a seventh axis Ax1 passing through a point Pn7coordinates of which are (60, 0) and a point Ps7 coordinates of whichare (−60, 180), (8) an eighth axis Ax8 passing through a point Pn8coordinates of which are (45, 0) and a point Ps8 coordinates of whichare (−45, 180), (9) a ninth axis Ax9 passing through a point Pn9coordinates of which are (30, 0) and a point Ps9 coordinates of whichare (−30, 180), (10) a tenth axis Ax10 passing through a point Pn10coordinates of which are (15, 0) and a point Ps10 coordinates of whichare (−15, 180), (11) an eleventh axis Ax11 passing through a point Pn11coordinates of which are (75, 90) and a point Ps11 coordinates of whichare (−75, 270), (12) a twelfth axis Ax12 passing through a point Pn12coordinates of which are (60, 90) and a point Ps12 coordinates of whichare (−60, 270), (13) a thirteenth axis Ax13 passing through a point Pn13coordinates of which are (45, 90) and a point Ps13 coordinates of whichare (−45, 270), (14) a fourteenth axis Ax14 passing through a point Pn14coordinates of which are (30, 90) and a point Ps14 coordinates of whichare (−30, 270), and (15) a fifteenth axis Ax15 passing through a pointPn15 coordinates of which are (15, 90) and a point Ps15 coordinates ofwhich are (−15, 270), the steps (a) to (h) being the steps of (a)assuming a great circle that is present on the surface of the phantomsphere and is orthogonal to the axis Ax, (b) assuming two small circlesthat are present on the surface of the phantom sphere, that areorthogonal to the axis Ax, and of which absolute values of centralangles with the great circle are each 30°, (c) defining a region, of thesurface of the golf ball, which is obtained by dividing the surface ofthe golf ball at these small circles and which is sandwiched betweenthese small circles, (d) determining 30240 points, on the region,arranged at intervals of a central angle of 3° in a direction of theaxis Ax and at intervals of a central angle of 0.25° in a direction ofrotation about the axis Ax, (e) calculating a length L1 of aperpendicular line that extends from each point to the axis Ax, (f)calculating a total length L2 by summing 21 lengths L1 calculated on thebasis of 21 perpendicular lines arranged in the direction of the axisAx, (g) obtaining a transformed data constellation by performing Fouriertransformation on a data constellation of 1440 total lengths L2calculated along the direction of rotation about the axis Ax, and (h)calculating a peak value and an order of a maximum peak of thetransformed data constellation, a minimum value of 15 orders obtained byexecuting the steps (a) to (h) is not less than 27, a maximum value ofthe 15 orders obtained by executing the steps (a) to (h) is not greaterthan 37, and an average of the 15 orders obtained by executing the steps(a) to (h) is not less than 30 and not greater than
 34. 2. The golf ballaccording to claim 1, wherein an average of the 15 peak values obtainedby executing the steps (a) to (h) is not less than 200 mm.
 3. The golfball according to claim 1, wherein a total volume of the dimples is notless than 450 mm³ and not greater than 750 mm³.